Device for sterilizing inoculation needles and loops



DEVICE FOR STERILIZING INocULATIoN NEEDLES AND LooPs April l, 1969 T. E. wElcHsl-:LBAUM ETAL Filed June 25, 1965 United States Patent O 3,436,171 DEVICE FOR STERILIZING INOCULATION NEEDLES AND LOOPS Theodore E. Weichselbaum, St. Louis, and Philip L. Varney, Florissant, Mo., assignors to Biological Research, Inc., a corporation of Delaware Filed .lune 25, 1965, Ser. No. 466,931 Int. Cl. A611 3/00 U.S. Cl. 21-85 4 Claims Y ABSTRACT OF THE DISCLOSURE A device for sterilizing inoculating needles and loops which is capable of igniting microorganisms on the needles and loops While preventing spattering of the microorganisms to the surrounding atmosphere. The device comprises an electrically heated combustion chamber open at one end for receiving the inoculating needles and loops. The other end of the chamber is inclined downwardly and is provided with retaining means for preventing the needles -and loops from sliding out. The retaining means is provided with a combustion air inlet which is covered with a spatter shield preventing spattering of microorganisms through the inlet but having air passages allowing air ow to the inlet.

This invention relates to a device for sterilizing inoculation needles and loops and more particularly relates to a device for igniting microorganisms on such needles or loops before and/or after use of the needles or loops in microorganism transfer procedures.

It is common practice in microbiology laboratories to use inoculating needles and loops for transferring microorganisms from a culture to a nutrient medium or the like, eg. for eventual isolation of the organism. An inoculating needle or loop is an elongate member having a handle at one end and a microorganism-carrying portion at the other end. The microorganismi-carrying portion is usually .a blunt ended platinum wire needle or a length of platinum wire having a loop formed at the end. In use, the microorganism-carrying end is contacted with the microorganism desired to be transferred and is then contacted with the nutrient medium to which the transfer is desired.

After use, the inoculating needles or loops :are cleaned or sterilized for reuse. This is usually accomplished by igniting the microorganism-calrying end in the open flame of a Bunsen burner. However, such ignition with direct flame causes immediate boiling, spattering and volatilization of the microorganism material which is usu-ally a suspension of organic material in water. Such spattering and volatilization spreads the microorganism to areas about the llame or even throughout an entire laboratory or building and may cause contact with laboratory or other personnel. This can be very dangerous, especially where pathogenic fungi and pathogenic :bacteria are involved.

It is a general object of this invention to provide a new and useful device for sterilizing inoculating needles and loops.

It is a more particular object of this invention to provide a new `and useful device for igniting, and thereby destroying, microorganisms on inoculating loops and needles without spreading the microorganisms by spattering or the like.

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Another object of this invention is to provide a device for receiving and holding inoculating loops and needles and which is capable of igniting the loops and needles while containing microorganisms against escape until the microorganisms are fully destroyed.

It is a further object to provide a device according to any of the foregoing objects, in which device the inoculating needles and loops can be readily inserted andare supported during ignition, and from which device the loops and needles can be easily recovered after ignition.

In a preferred form of this invention, it is an object to provide a highly etlicient device according to any of the foregoing objects, which device has a low current requirement for use in microbiology laboratory to perform the sterilization within a reasonable length of time without requiring special high current wiring.

VOther objects and improved features of this invention will be apparent from the following description and the drawings, in which:

FIGURE l is -a side elevational view of a form of inoculating loop and needle sterilizing device, according to this invention;

FIGURE 2 is an enlarged section along line 2 2 of FIGURE l; and

'FIGURE 3 is -a section along line 3 3 of FIGURE 2.

While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail a specific embodiment of t-he invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated.

Turning rst to the specific exemplary embodiment of the device of this invention as illustrated in the drawings, with reference to FIGURE l, the device includes a weighted c-ast aluminum base 12 having lan upstanding hollow cast support post 13 received and secured in a bore in the top of base 12. The upper end of post 13 is ared or expanded as at 14 and has a concave receptacle 1S (FIGURES 1 and 2.) on the upper end for receiving and supporting an incinerator assembly 16 on an incline. Self-threading screws 17 secure the incinerator lassem- -bly 16 to flared end 14.

As seen in better detail in FIGURES 2 and 3, the incinerator assembly 16 includes a foraminous or perforated tubular cooling shield or guard 1S which comprises a foraminous stainless steel sheet formed into a tube land having an overlap at 18a (FIGURE 2). Screws 17 are secured through the overlap 18a. A circular end cap 19, formed from aluminum sheet material, is provided on each end of the shield 118 and is secured to the shield 18 by self-threading screws 22 to hold shield 18 in its tubular conguration. Each end cap 19 has a central opening 23.

Heat-transmitting Wall means dene a heater tube 24 disposed centrally within shield 18. A heating coil 25 is wound around tube 24, and a tubular layer of insul-ation 26 is provided over the heating coil 25. Support rings 27 receive the ends of the tubular layer of insulation 26 and are secured to the end caps 19 by suitable screws 28 to support the combination of tube 24, coil 25 and insulation 26 generally centrally within shield 18.

In the form illustrated, the heating coil 25 is wound generally evenly over the exterior of tube 24 to provide even heat on the interior surface of tube 24 along the length of the tube wall. The tube 24 is of an infra-red heattransmitting material such as Vycor glass, a high silica glass, providing an inner tube surface which is a very smooth and even heating surface. A ceramic plug 29 is provided in one end of tube 24, i.e., the lower end of tube 24 with tube 24 disposed on the incline shown in FIG- URE l, so that inoculating needles or loops inserted from the other end of tube 24 will rest in tube 24 with their microorganism-carrying ends resting against plug 29 and their handled ends extending from the upper unplugged or open end of tube 24 so that the needles can be readily recovered.

It will be noted that plug 29 has a central combustion air inlet port 32 which is preferably sized for permitting entry of a minimum amount of combustion air needed for burning the microorganisms with the device loaded to capacity with microorganism bearing loops or needles. The air entering port 32 flows through tube 24 by convection during operation of the device. An end cap 30 is secured by screws 28 to enclose the outer end of port 32 and completely blocks escape of spattering microorganism from port 32 but has air flow passages 31 for permitting entry of air into port 32. The inner surface of tube 24 is the Vycor glass surface.

Base plate 35 is secured Iby screws 36 to the bottom of the base 12 forming a generally enclosed cavity in base 12. Electrically conductive wires 37 lead from la wall plug 38 or other suitable source of electricity through an on-off toggle switch 39, thence through hollow column 13, a port 42 in shield .18, and through the insulation 26, as lead wires to coil 25 for supplying electricity to coil 2S.

For operation, switch 39 is turned to on position and coil 2S immediately produces infra-red heat which penetrates the wall of tube 24 to evenly heat the inner surface of tube 24 over the length of tube 24. The needles or loops are then inserted, microorganism-carrying end irst, into the unplugged upper end of tube 24 which protrudes through opening 23. During sterilization the loops or needles are hand held by their handled ends which project from the open end of tube 24 while the microorganism-carrying ends are near ceramic plug 29. The incline of tube 24 is at a proper angle for convenient insertion of the loops or needles and for maintaining iiow of sufiicient lair into port 32 by convection to supply cornbustion air within tube 24 and remove combustion gases from the open end of the tube. The infra-red heat, radiating the loop and needle ends, is not materially affected by the ow or draft of air through the tube.

Also, the incline and length of the tube 24 are proper for inhibiting or blocking the spattering of the microorganisms through the open end, and port 32 is of sufvlicient small diameter and sufficient length to inhibit or block spattering through port 32; the updraft through port 32 may also help some in preventing escape of spattering microorganisms through port 32. The angle of ineline is not critical, but the optimum angle in any device will depend to a large extent on the arrangement, shape and size of the various compenents of the device. The angle is preferably such as to make insertion and withdrawal of needles and loops easier with the device resting on a laboratory bench of conventional height.

The device described above has been successfully used in sterilizing inoculating needles and loops. The smooth inner surface of the tube 24 is advantageous in lessening abrasion of the needles and loops during their insertion and withdrawal. The wall of tube 24 is transparent to infra-red and permits instantaneous transfer of infra-red heat so that optimum sterilizing temperatures can be reached within a matter of a few minutes, after switch 39 is turned on.

In a model of the illustrated device, tube 24 was about 0.5 inch in inner diameter and 6 inches in length, mounted at a 17 degree incline. Insulation 26 was 5% inches long, spaced 1A; inch from the plugged end and 1A; inch from the open end of tube 24. Coil 25 extended between positions spaced inward 1A; inch from the ends of insulation 26 POft 32 W35 1/2 inch in length and 3 mm. in diameter.

The structure had a current consumption of less than 0.9 ampere and required less than Watts at a maximum voltage of volts, yet the device attained sterilization temperatures of about 1600 F. The low current requirement is advantageous in that la number of the devices can be run from one ordinary house circuit in a microbiology laboratory.

In use of the device, a 4ring of Petri dishes containing a suitable nutrient was placed around the device during sterilization operations using loops having Staphylococcus albus on the microorganism-carrying ends, and it was determined that microorganisms did not escape from the device to the Petri dishes. In conducting a similar experiment while using the open-ame Bunsen burner method of igniting a loop, the burner was ringed with Petri dishes containing the nutrient, and it was found that the Staphylococcus albus was transferred to the nutrient material in the dishes.

We claim:

1. A device for sterilizing inoculating needles and loops which comprises heat-transmitting wall means defining a receptacle for receiving and containing inoculating loops and needles lbearing microorganisms, means outside said receptacle for heating said wall means over generally the entire inner surface of said wall means to microorganism ignition temperature, means for mounting said receptacle at an incline, retaining means at the lower end of said receptacle for retaining inoculating loops and needles against sliding from said lower end, a combustion air inlet through said retaining means, and a spatter shield means covering said inlet for preventing dissemination of microorganisms spattering through said inlet but having air passage means for permitting free flow of air to said inlet from outside said spatter shield means, the incline of said receptacle and the size of said inlet being such as to permit an updraft through said receptacle, when heated, of a minimum amount of air sufficient for burning the microorganisms when said receptacle is loaded to capacity with microorganism bearing loops and needles.

2. A device for sterilizing inoculating needles and loops which comprises an incinerator assembly including: an elongate tubular receptacle having an infra-red heat-transmitting wall, said receptacle having an open end for receiving inoculating loops and needles bearing microorganisms and a combustion air inlet end, infra-red electric resistance heater coil means surrounding said receptacle lfor heating said receptacle to microorganism ignition temperature, insulation means surrounding said coil means for minimizing escape of heat, foraminous covering shield means spaced from and .surrounding said insulating means, means supporting lsaid insulating means, coil means and receptacle from said covering shield means, retaining means at said combustion air inlet end of said receptacle for retaining inoculating loops and needles within said receptacle, a combustion air inlet through .said retaining means', and spatter shield means covering said inlet for preventing dissemination of microorganisms spattering through said inlet but having air passage means for permitting Afree ow of air to said inlet from outside said spatter .shield means; means for supplying electric power to said coil; and means for supporting said incinerator assembly with said receptacle on an incline and with the combustion air inlet end of said receptacle as the lower end; the incline of said receptacle and the size of said inlet being such as to permit an updraft through said receptacle, when heated, of a minimum amount of an' suicient for burning the microorganisms when said receptacle is loaded to capacity with microorganism bearing loops and needles.

3. The device of claim 2 wherein said means Afor supporting said incinerator assembly comprises a weighted base member and a hollow support post secured to said base member and mounting said incinerator assembly by said covering shield means.

4. The device of claim 3 including switch means mount- 1,625,487 4/ 1927 Meyer 219-521 XR ed on said base for controlling the supply of electric 3,311,694 3/ 1967 Lasch 219-407 XR power by said supplying means to said coil.

MORRIS O. WOLK, Primary Examiner. References Cfed p 5 BARRY s. RICHMAN, Assistant Examiner. UNITED STATES PATENTS l 699,146 5/1902 Carr. US- Cl- X-R' 1,505,726 8/1924 lOpperman 219-521 13--22; 21--54, 82, 92, 102; 195-119, 120; 219-390, 1,530,199 3/1925 Opperman 219-390 411, 521 

